Edexcel A Level Geography - Water Cycle

what is the hydrological cycle known as

a system comprised of

stores - the holding of water

flows - measure the rate of flow between stores

processes - physical factors that drive the water

what drives the hydrological cycle

Solar energy and gravitational potential energy

what is the global water budget

the annual balance of water flows and the size of the water stores

what is residence time

the average time a water molecule will spend in a reservoir or store

how much percent of the earths water is stored in the ocean

97%

what is a drainage basin

an area of land drained by a river and its tributaries

what is a watershed boundary

an area of land that separates water flowing to different rivers

what is the ITCZ

inter tropical convergence zone, it is a low pressure belt encircling the Earth, near the equator, it moves and impacts precipitation

the 3 cells around the earth giving different temperatures at different latitudes

polar - 60-90 degree

ferrel - 30-60 degree

hadley - 0-30 degree

what is convectional rainfall

Due to heating by the sun, warm air rises, condenses at higher altitudes and falls as rain

what is orographic rainfall

caused by uplifting and cooling of moist air over mountains

what is frontal rainfall

when a warm air mass meets a cold air mass, forcing the warmer air to rise and cool over the denser air

The UK's rainfall

the tees- exe line separates the rainfall of the UK, with orographic rainfall mainly happens in the west, and convectional in the south, but over a year, frontal rainfall brings the most to the whole UK

how does deforestation affect the drainage basin

reduces evapotranspiration, less ground water to aid in dry days, rainwater runs quickly, flooding

3 human factors affecting a drainage basin

deforestation, urbanisation reservoirs

how does urbanisation affect a drainage basin

buildings have far more run off than nature at 55% to 10%, and far less infiltration and deep infiltration

how does reservoirs affect a drainage basin

they are man made, that interrupt the flow of water, reduce river flow, e.g Kenya tana river flood plain forest is dying lack of floods upstream

what physical factors affect a drainage basin

vegetation cover

temperature

geology

soil type

what is the only input to a drainage basin

precipitation

what physical factors affect the Thames river basin, UK

annual precipitation - 600-750mm/year

soil/rock type - sedimentary rocks

what human factors affect the Thames river basin, UK

land use - urban, agriculture, transport

pollution - sewage run off

flood risk

Thames barrier - for tidal flood control

population pressure - 15million+ in basin

what physical factors affect the toncantis river

Tropical climate - 2000 + mm/year

dense rainforest, allows for high interception and evapotranspiration

what human factors affect the toncantis river

Tucurui Dam one of the worlds largest, alter river flow and increase flood risk

deforestation increases run off

agriculture near the river, pollutes river, reduces interception

what is the water budget

show the annual balance between inputs and outputs

What does the water budget graph show

what is precipitation

rain, snow, sleet, or hail that falls to the ground.

what is interception

A temporary storage whereby water is captured by plants and buildings before reaching the ground.

what is surface storage

water in lakes, ponds, puddles

what is ground water storage

water held within permeable rocks

what is percolation

When water moves vertically down through soil and rock

what is evapotranspiration

the combined effect of evaporation and transpiration

what is river discharge

The volume of water passing a measuring point in a given time.

what is a river regime

the difference in the discharge of the river throughout the year

what is a simple regime

One where a river has a period of seasonally high discharge (glacier melt, monsoons), followed by low discharge.

what is a complex regime

One that is affected by many variables because they are larger and cross several relief and climatic zones. they are affected by human factors

River Yukon - Alaska - regime

complex, low discharge until may, snow melt contribute to rising river levels, peak discharge in june of 16000, then starts to drop after june until winter months and refreeze

River Amazon - West of South America to east - regime

complex, peak rainfall in feb/march direct sunlight (270mm), peak discharge in june despite rain at lowest, due to large basin + all tributaries to reach, fall in convectional rainfall june-oct, tilt from sun

what is a flashy river

a river with a short lag time, fast flow, impermeable surface

what is a flat river

a river with a long lag time

what is a storm hydrograph

a graph that shows changes in discharge of a river over a short period of time

4 types of drought

meteorological - precipitation is below average

agricultural - lack of growth due to no rain

hydrological - lack of water supplies in streams

socioeconomic - the impact on the population

River Severn case study

longest river in the uk 354km, flow through wales, west england, regime seasonal variation, flow high in winter/spring due to rainfall/snowmelt

River Severn case study human impacts and the flood management

Human

building on floodplain

agricultural land

flood management

hard engineering in gloucester e.g levee/embankment

Mississippi River USA

One of the longest rivers in the world 3730km, from north usa to gulf of mexico

river regime - high variety, heavy rain in summer, snowmelt in spring peak, large drainage basin

Mississippi River USA human impact and flood management

human impact

loss of wetlands - natural storage reduced

flood management

river engineering - levee spilways

what is a anti cyclone

areas that experience intense high pressure and sinking air, pressure of 1008mb

What does ENSO stand for

El Nino Southern Oscillation

What is the ENSO cycle, where does it happen between

Movement of warm water mass in the equatorial Pacific Ocean

Australia to south America

what is the 'normal condition' in the pacific ocean

Warm water by Australia and east Aisa, causing warm air to rise, lots of rain

Cold water by South America, air sinks, high pressure and no rain

What is La Nina

the process of intensifying normal conditions

What is El Nino

Weather patterns swap, heavy rainfall in S America, Droughts in Australia

What does over abstraction mean

the amount of water used has been too much and not enough has been replenished, leads to water scarcity.

what is a aquifer

body of permeable rock that can hold or transmit ground water.

what is a confined aquifer

covered by permeable rock deep down, hard for water to get to

what is a unconfined aquifer

a groundwater layer with no impermeable barrier above it.

impact of over abstraction

water reduce in layers

water quality falls

water table sinks

England water situation - drought 2025

water crisis caused by plant watering, over abstraction, heat caused water sources to dry up, will need mass rainfall to replenish as a dry year one year can cause be a threat if a drought happens next year, water tables significantly lower

how can humans increase drought risk

deforestation

over-abstraction

impact of deforestation on drought risk

deforestation = no evaporation = less rainfall = decrease in discharge

what does ecosystem functioning mean

the biological, physical and chemical processes that take place within an ecosystem.

impact of drought on forest

younger trees die, canopy cover reduces, exposing dry surface litter fire prone.

what caused the 2014-15 Brazil drought

anti cyclone blocking rain bearing winds away from the amazon, deforestation, less transpiration.

what impact did the Brazil 2014-15 drought have

reduced crop of arabica coffee beans - global coffee price up by 50%

groundwater extraction up - aquifers low

fall in HEP production -

What caused the 2019-20 Pantanal wetland drought

140,000km2. Anti cyclone caused high pressure. 192% increase in wildfires from 2019. ground litter exposed.

What impact did the 2019-20 Pantanal wetland drought have

40m reliant on the river. over 70,000 km 2 burned. agriculture and ecosystem suffers. Breathing issues from smoke. Burned trees, release co2, less transpiration. Exposed ground, heat up and cause lowering water tables, kill vegetation

what does surface water flooding mean

flooding that occurs when intense rainfall has not enough time to infiltrate the soil , flows overland

what does groundwater flooding mean

prolonged heavy rain, cause land to become saturated, as a result floods happen

what does flash flooding mean

high level of rain, short lag time flood

physical causes of flooding

amount and type of rainfall - influence intensity of rain

impermeable material

relief ( land angle )

human causes of flooding

urbanisation

deforestation

land use

infastructure

what physical and human factors caused the Texas flood keer county - 4-5th July 2025

physical - flash flood, 200mm + rain in hours, river rose 8m in 1 hour, steep terrain accelerated water

human - built on a vulnerable flood plain

impacts of the Texas flood keer county - 4-5th July 2025

130 deaths - 200 missing

poor land use planning, flash flood in HIC area

loss of habitats

what physical and human factors caused the Pakistan monsoon flood June-October 2022

physical - flash flood exacerbated by climate, monsoon rainfall and glacier melt from Himalayas mountain cause river indus over load

human - deforestation, poor land management

impacts of the Pakistan monsoon flood June-October 2022

33m+ displaced 1300 deaths

$15B loss

crops loss and submerged, food insecurity worsen

what physical and human factors caused the west Germany and east Belgium 12-15 July 2021 flood

physical - low pressure system, intense rainfall, 150mm over 24h, caused river ahr overload

human - climate change made this disaster 9x more likely to occur.

impacts of the west Germany and east Belgium 12-15 July 2021 flood

200 deaths

€30B loss in Germany alone

habitat loss

What physical and human factors caused the oxford Jan 2024 floods

physical - surface water flooding, storm Henk cause river Cherwell and Thames overflow, saturated soil, higher flood risk, more run off

human - impermeable surface, city expansion.

impacts of the oxford Jan 2024 floods

no deaths

road closure

city loss of businesses.

polluted water systems.

what physical and human factors caused the Nigeria July - October 2022 flood

physical - shift in ITCZ north, heavy rainfall in N, monsoon season

human - Cameroon lagdo dam overflow, flows into Benue river Nigeria and floods.

impacts of the Nigeria July - October flood 2022

600+ died, 1.3m displaced

food inflation rise

agriculture land flood, soil erosion, 50% water contaminated.